DESCRIPTION: Presbyopia is a reduction in the ability to focus close and is an inevitable consequence of aging. Though of long-standing interest, the principle cause for this loss of function is still in doubt. Much of the doubt stems from the inability to measure the changes that occur with age in the structures that mediate focusing: the lens, its related muscle, and its supporting elements. High resolution magnetic resonance imaging of the eye, using specialized techniques developed by the investigators is the only method that can provide certain critical information. Specifically, high resolution MR imaging can show how the peripheral lens and its support structures change with the effort to focus in both the normal and presbyopic eye. This important information will be used to evaluate several contemporary theories of presbyopia. In addition, a computer-based model of the human focusing mechanism will be developed to link the geometrical data obtained from MR images with mechanical data obtained in previous in vitro studies. This analysis should provide a good picture of the structural changes that lead to presbyopia and provide essential background information toward the ultimate goal of retarding or reversing this functional loss.